A study on effectiveness of inorganic and organic corrosion inhibitors on rebar corrosion in concrete: A review

Reinforced concrete is the most extensively used building material in the construction industry. Generally, well-made concrete provides good physical and chemical protection to the embedded steel bar against an aggressive environment. The highly alkaline concrete pore solution protects the steel reinforcement from aggressive ions by forming a passive oxide layer over the steel surface. However, the passive film can be destroyed, and corrosion of steel reinforcement can be initiated either due to carbonation or due to the presence of a sufficient amount of chloride ions at the rebar level. Chloride induced corrosion of steel reinforcement affects the durability and decreases the service life of reinforced concrete structures exposed to aggressive environments, which results in huge repair and maintenance costs. By keeping in view, the substantial economic loss incurred due to corrosion of steel reinforcement in reinforced concrete structures, it is necessary to adopt adequate measures to minimize the corrosion of steel reinforcement in concrete. The most common corrosion prevention technique is the use of corrosion inhibitors in concrete. Several research works have been reported in the literature to evaluate the efficiency of corrosion inhibitors against chloride-induced corrosion of steel reinforcement in concrete. Corrosion inhibitors are typically introduced either as an admixture during the preparation of fresh concrete mixes or as a surface application on the hardened concrete to prevent the onset of corrosion of steel reinforcement or extend the corrosion initiation time in reinforced concrete structures. This review article summarizes the reported research works on inhibiting the behaviour of organic and inorganic corrosion inhibitors against chloride-induced corrosion of steel reinforcement in simulated concrete pore solution such as saturated calcium hydroxide solution containing varying concentrations of chloride ions as well as in cementitious composites. Further, the reported research works on the effect of corrosion inhibitors on the mechanical properties of cementitious composites are also are reviewed and discussed.